Two-center electron emission in collisions of fast, highly charged ions with He: Experiment and theory

Abstract

Electron emission cross sections differential in energy and angle of the ejected electrons were measured in collisions of 5-MeV/u ${\mathrm{C}}^{6+}$, ${\mathrm{O}}^{8+}$, and ${\mathrm{Ne}}^{10+}$ ions on He. The experimental results deviate substantially from calculations based on the plane-wave Born approximation indicating that the ejected electrons are significantly affected by the two-center field of the target and projectile ion. The two-center effects were confirmed by comparison with results from the continuum-distorted-wave--eikonal-initial-state (CDW-EIS) approximation that has recently been improved by using Hartree-Fock-Slater wave functions for the ejected electrons. It is shown for nearly complete energy and angular ranges that the improved CDW-EIS method predicts cross sections in excellent agreement with experiment.